There are many types of air filtration devices for internal combustion engines on the market today. One example is an automotive air filtration unit offered on the Ford Mustang model year 2000 in which a rectangular cross section housing is provided at the upstream inlet end of the engine air intake manifold located on the left side fender well under the hood of the vehicle. This box-like housing has disposed within it an air filtration element in the form of a frustoconically shaped filter media with a blunt, imperforate nose of say three inches in diameter at its leading end. This filter media diverges from its nose in a conical shape with a straight taper to a diameter of about four or five inches at its rear end, and is approximately six to seven inches long. The conical surface of this filter is pleated, and the smaller diameter, blunt nose of the filter media is oriented as the leading end of the filter, thus facing upstream in the air flow stream being engine-drawn into the intake manifold.
One of the problems discovered with this prior art filter is caused by the nonconformance geometrically between the general conical shape of the filter media versus the generally rectangular shape of the enclosing housing. This configuration presents a relatively high level of air deflection and creates turbulence and eddies that also contribute to deposit collection of contaminating particles in certain areas of the housing, thereby reducing the efficiency of the filter relative to air flow capacity. Also, the audible noise level associated with such air filtration devices is objectionably high in some instances and under certain conditions. The aforementioned filter-housing configuration also reduces the air flow velocity through the filter due to the air flow deflections and turbulence effects. Conditions of velocity changes in air flow, depending on the engine demand, also typically change the interface angle between the impinging air and the filter surface, further reducing optimum performance of the filter.
Other examples of prior art automotive air filtering devices are those shown in the U.S. design patents DES. No. 401,597; DES. No. 401,942; DES. No. 403,414 and DES. No. 403,416.